Mobile work machine

ABSTRACT

The invention relates to a wheeled working machine, particularly a truck-mounted concrete pump, comprising a chassis ( 10 ) that is designed as a semi-trailer. The semi-trailer encompasses a tractor ( 12 ) and a multi-axle trailer ( 14 ) which is connected to the tractor ( 12 ) by means of a fifth wheel ( 16 ) and carries the working machine. A support structure ( 38 ) located in the area of the trailer ( 14 ) can be supported on a ground ( 40 ) while the semi-trailer is lifted. The support structure ( 38 ) comprises two front support booms ( 42′, 42″ ) and two rear support booms ( 44 ) which can all be swiveled relative to the trailer ( 14 ) between a transported position and at least one supporting position. Furthermore, means for lifting and blocking the tractor ( 12 ) are arranged on the trailer ( 14 ) such that the tractor ( 12 ) forms a ballast in the supporting position in order to stabilize the trailer ( 14 ) that is supported on the ground ( 40 ) with the help of the support structure ( 38 ). According to the invention, the actuating mechanism of each front support boom ( 42′, 42″ ) has a cylinder-piston unit ( 54′, 54″ ) which is designed as a hydraulic cylinder and extends across a front part ( 52 ) of the trailer ( 14 ). One end of the cylinder-piston unit ( 54′, 54″ ) is directly hinged to a bearing eye ( 56′, 56″ ) that is fixedly mounted on the trailer ( 14 ) while the other end thereof is indirectly hinged to the associated support boom ( 42′, 42″ ) by means of a deflection gear ( 58′, 58″ ).

The invention relates to a mobile work machine having a chassis that isdesigned as a tractor-trailer, a multi-axle tractor unit and amulti-axle semi-trailer that carries the work machine and is connectedwith the tractor unit by means of a fifth-wheel coupling, having asupport construction that is disposed on the semi-trailer and can besupported on a surface, raising the tractor-trailer, which constructionhas two front support booms disposed at bearing locations on the tractorunit end of the semi-trailer, symmetrical to the longitudinal chassisaxis, which can be pivoted between a transport position parallel to thelongitudinal chassis axis, and at least one support position, by meansof an activation mechanism, and two rear support booms that can beadjusted between a transport position and at least one support position,whereby the semi-trailer has means for raising and/or holding thetractor unit in place.

A mobile work machine of this type, configured as an automatic concretepump, is known (EP 0 038 958 B1), in which the support booms of thesupport construction are disposed laterally on the semi-trailer and canpivot in such a manner that they can be pivoted out from a transportposition into a support position, and can be telescoped, if necessary. Alatch ensures that both a vertical and a horizontal transfer of force ispossible by way of the fifth-wheel coupling, and that the tractor unitcan nevertheless be pivoted about the vertical axis of a king pin,relative to the semi-trailer. A rotary bearing that is additionallyprovided on the fifth-wheel coupling allows a nodding movement of thetractor unit about a horizontal transverse axis, relative to thesemi-trailer. In order to be able to use the tractor unit as a ballastweight in the raised position of the chassis, to stabilize thesemi-trailer that is supported on the ground with the support booms,means for raising the tractor unit and holding it in the raised positionare provided on the fixed part of the semi-trailer, which means have alever there, which can be pivoted by means of a hydrocylinder, as wellas a limp pulling organ that is disposed between the lever and thetractor unit.

The invention is based on the task of improving a mobile work machinehaving a chassis designed as a tractor-trailer, of the type indicatedinitially, to the effect that coupling or uncoupling of the tractor unitwith or from the semi-trailer is facilitated, and that the clear spaceavailable for the semi-trailer can be optimally utilized foraccommodating activation elements for the support construction.

In order to accomplish this task, the combination of characteristicsindicated in claim 1 is proposed. Advantageous embodiments and furtherdevelopments of the invention are evident from the dependent claims.

The solution according to the invention is based on the recognition thatin the case of large tractor-trailers, in particular, a sufficientlylarge clear space is available between the face end of the semi-trailerand the driver's cab of the tractor-trailer, which space is sufficientfor accommodating essential parts of the activation mechanism for thefront support booms, so that the height of the semi-trailer and of itssuperstructure can be reduced. This is particularly advantageous if alarge distributor mast, having a total length of 65 m and more, issupposed to be accommodated on the semi-trailer, in the case of mobileconcrete pumps. In order to achieve this, it is proposed, according tothe invention, that the activation mechanism of each front support boomhas a cylinder/piston unit configured as a hydrocylinder, which extendsbeyond the face part of the semi-trailer, which unit is articulated, atits one end, directly with a bearing eye that is fixed in place on thesemi-trailer, and, at its other end, indirectly with the related supportboom, by way of a deflection gear mechanism.

A preferred embodiment of the invention provides that thecylinder/piston units assigned to the two front support booms aredisposed one above the other, on the face of the semi-trailer, facingtoward opposite sides. Since the cylinder/piston units can be pivotedabout articulation axes that run parallel to the vertical axis, at theirtwo ends, they engage at a slant into the clear space between the faceof the semi-trailer and the driver's cab during the course of theextension procedure of the front support booms. It is advantageous ifthe bearing eyes of the cylinder/piston units assigned to the two frontsupport booms, which eyes are fixed in place on the semi-trailer, aredisposed on the side of the semi-trailer that faces the other frontsupport boom, in each instance, preferably in the vicinity of therelated bearing location.

A preferred embodiment of the invention provides that the deflectiongear mechanism assigned to the activation mechanism of each support boomhas a deflection lever that can be pivoted about an articulation axisparallel to the extension axis of the support boom, on an articulationthat is fixed in place on the semi-trailer, with its one end, whichlever has articulation locations at its other end, on which thecylinder/piston unit as well as the one end of a rigid extension rod arearticulated, whereby the extension rod is articulated, with its otherend, on an articulation location of the support boom disposed at adistance from the bearing location. It is practical if the articulationlocations for the cylinder/piston unit and the extension rod that aresituated on the deflection lever are disposed at a slight distance fromone another. In order to be able to activate the activation mechanism sothat it does not become constricted, all the bearing and articulationaxes of the activation mechanism should be oriented parallel to theextension axis of the related support boom.

Because of the kinematics of the activation mechanism according to theinvention, a constant feed of pressurized oil to the cylinder/pistonunit would lead to a non-uniform angular velocity when the front supportlegs are pivoted out. In particular, at the beginning of each extensionprocedure, from the transport position of the support boom, a relativelylarge pivot path of the support boom would already occur at a smalladjustment path of the cylinder/piston unit. In order to avoid this, itis proposed, according to a preferred embodiment of the invention, thatthe feed of pressurized oil to the cylinder/piston unit can be changedas a function of the angular position of the related front support boomor deflection lever. It is advantageous if this takes placeautomatically in that a throttle valve is disposed in a pressure agentfeed line to the cylinder/piston unit, which valve can be controlled byway of a switching organ that responds in a defined angular position ofthe support boom or of the deflection lever.

In order to allow both normal support and narrow support of the supportbooms, the support booms have a releasable stop in a first supportposition that defines a normal position, and an end stop in a secondsupport position.

According to a preferred embodiment of the invention, the work machineis configured as a concrete pump that has a pump unit disposed on thesemi-trailer, having a material application container and a feed linethat is connected with the pressure output of the pump unit, guided byway of a distributor mast.

It is practical if the work machine, configured as a concrete pump, andthe support booms of the support construction, are disposed on at leastone superstructure frame that is connected with the chassis that formsthe semi-trailer. It is advantageous if an internal combustion enginethat is independent of the drive of the tractor unit is disposed on thesuperstructure frame, for drive of the hydraulic units that belong tothe concrete pump.

The invention is furthermore based on the idea that the tractor unit,which is connected with the semi-trailer by way of the fifth-wheelcoupling, and can be pivoted relative to the semi-trailer about thevertical axis of the king pin, can be raised from the ground with simplemeans, together with the semi-trailer, during the stabilizing process,and can be utilized as a ballast weight. In order to allow this, it isproposed, according to a preferred embodiment of the invention, that thebearing locations of the support booms have a continuous, axis-centralcavity, and that the means disposed on the semi-trailer for raising andholding the tractor unit in place each have a lifting element thatpasses through the central cavity of the bearing locations, from top tobottom, and can be fixed in place on the tractor unit. In thisconnection, it is practical if the cavity for the lifting element isdisposed in a bearing pin that is fixed in place on the support boom.

A preferred embodiment of the invention provides that the liftingelements, which can be raised and lowered by means of a motor, in eachinstance, carry a coupling organ at their lower end, and that thetractor unit has an auxiliary frame on which the coupling organs of thelifting elements can be locked in place. In this connection, it ispractical if the lifting elements are coupled with the related motor byway of a linear drive, in each instance, whereby the linear drivepreferably has thread parts configured as a trapezoid thread.

Another preferred embodiment of the invention provides that thefifth-wheel coupling has a king pin disposed in the center, forming avertical pivot axis between tractor unit and semi-trailer, and that theauxiliary frame is configured in the shape of an arc, in its outline,and disposed concentric to the king pin, and has multiple lockinglocations for the coupling organs of the lifting elements, disposed at adistance from one another in the circumference direction. With thismeasure, it is possible, in particularly simple manner, to raise thetractor unit from the ground at different angles oriented relative tothe semi-trailer, during the course of the stabilizing process. It isadvantageous if the coupling organs are fixed in place on the lockinglocations of the auxiliary frame by means of socket pins. For thispurpose, the coupling organs are configured as oval rings that can berotated and/or pivoted on the lifting element, which rings can beintroduced into an arc-shaped motion-link guide of the auxiliary frameand can be fixed in place there, at the locking locations. In thisconnection, the locking locations form a hole grid in the auxiliaryframe, which runs in the circumference direction, on the holes of whichthe oval rings can be fixed in place by means of socket pins. With thelifting elements coupled onto the auxiliary frame, the result isachieved that the wheels of the tractor unit can be raised from theground during the stabilization process. In the travel state, thefifth-wheel coupling ensures that the tractor unit can perform a noddingmovement relative to the semi-trailer, in order to be able to overcomeunevenness of the road. For this purpose, the coupling organs of thelifting elements must be uncoupled from the auxiliary frame. In order toprevent damage in the travel state, the coupling organs can be retractedinto the cavity of the related bearing locations, by means of a motor,by way of the lifting element, in each instance.

In the following, the invention will be explained in greater detailusing an exemplary embodiment shown schematically in the drawing. Thisshows:

FIG. 1 a diagrammatic representation of a mobile concrete pump in thestate of road travel, with support legs pivoted in and distributor mastcollapsed;

FIG. 2 a a top view of the front part of the mobile concrete pump, withdistributor mast removed and front support legs pivoted in;

FIG. 2 b a diagrammatic representation of the front part of the mobileconcrete pump according to FIG. 1, with front support legs pivoted out;

FIG. 3 a to c a diagrammatic representation, a face view, and a top viewof the front part of the semi-trailer, with support legs pivoted in;

FIGS. 4 a and b a detail of a face front view and a bottom view of thesemi-trailer, with a front support leg pivoted out, into the normalposition, in a diagrammatic representation, in each instance;

FIGS. 5 a and b representations corresponding to FIG. 4 a and b, with afront support leg pivoted out, in the narrow support position;

FIG. 6 a a detail of a diagrammatic representation of thetractor-trailer with auxiliary frame and lifting mechanism;

FIG. 6 b a side view of the fifth-wheel coupling of the tractor-trailerconcrete pump, in a representation partly in section;

FIGS. 7 a and b a side view and a sectional representation of thelifting mechanism according to FIG. 6 a;

FIG. 8 a diagrammatic representation of the auxiliary frame removed fromthe tractor unit.

The mobile work machine shown in FIG. 1 is configured as a mobileconcrete pump, which has a chassis 10 designed as a tractor-trailer,consisting of a five-axle tractor unit 12 and a five-axle semi-trailer14. The tractor unit 12 is releasably connected with the king pin 18 ofthe semi-trailer 14, by way of a known fifth-wheel coupling 16 (see FIG.6 b). The latch 20 ensures that both vertical and horizontal transfer offorce is possible, by way of the coupling, and that the tractor unit 12can nevertheless be pivoted about the vertical axis of the king pin 18,relative to the semi-trailer 14. The rotary bearing 22 that isadditionally provided on the fifth-wheel coupling 16 allows a noddingmovement of the tractor unit 12 about a horizontal transverse axis,relative to the semi-trailer 14.

A distributor mast 30 that is articulated onto a rotating tower 24 andcan be rotated, together with the latter, about a vertical axis, by amotor, by means of a gear-wheel transmission 26, and can be unfoldedusing hydraulic means 28, is disposed on the semi-trailer 14, in thefront region; its concrete line 32 can have the liquid concrete to beconveyed applied to it by way of a material application container 34 anda pump unit 36.

A support construction 38 is disposed in the region of the semi-trailer14, and can be supported on a surface 40, raising the entiretractor-trailer. The support construction 38 has two front support booms42′, 42″ and two rear support booms 44, which can be supported on thesurface 40 by means of a telescoping support foot 46 that facesdownward, on the free end, in each instance. The front support booms42′, 42″ can be pivoted on two bearing locations 48′, 48″ disposed onthe tractor-side end of the semi-trailer 14, symmetrical to thelongitudinal chassis axis, between a transport position (FIG. 2 a) thatis parallel to the longitudinal chassis axis, and at least one supportposition (FIG. 2 b), while the rear support booms 44 can be pivoted onbearing locations 50 disposed in the center region of the semi-trailer14, between a transport position and at least one support position inwhich they are pivoted out to the side. Extension of the front and rearsupport booms takes place with hydraulic means, using a hydrocylinderand a suitable deflection gear mechanism, in each instance.

A unique feature of the invention consists in that the activationmechanism of each of the front support booms 42′, 42″ has acylinder/piston unit 54′, 54″ that extends beyond the face part 52 ofthe semi-trailer 14, configured as a hydrocylinder, which unit isarticulated directly onto a bearing eye 56′, 56″ that is fixed in placeon the semi-trailer, at its one end, and onto the related front supportboom 42′, 42″, indirectly by way of a deflection gear mechanism 58′,58″, at its other end. As can be particularly seen in FIG. 3 a to c, thecylinder/piston units 54′, 54″ assigned to the two front support booms42′, 42″ are disposed in the region of the face part 52 of thesemi-trailer 14, facing in opposite directions, one on top of the other,whereby the bearing eyes 56′, 56″ of the cylinder/piston units 54′, 54″assigned to the two front support booms 42′, 42″, which eyes are fixedin place on the semi-trailer, are disposed in the vicinity of thebearing location 48″, 48′ of the other front support boom 42″, 42′, ineach instance. The deflection gear mechanism 58′, 58″ assigned to theactivation mechanism of each front support boom 42′, 42″ has adeflection lever 62′, 62″ that can be pivoted about an articulation axisthat runs parallel to the extension axis in the region of the bearinglocations 48′, 48″ of the related support boom, on an articulation 60′,60″ that is fixed in place on the semi-trailer, with its one end, whichlever has two articulation locations 64′, 66′ and 64″, 66″,respectively, at its other end, in each instance. The second end of thecylinder/piston unit 54′, 54″ is articulated onto the articulationlocations 64′, 64″, in each instance, while the one end of a rigidextension rod 68′, 68″ is articulated onto the other articulationlocation 66′, 66″, whereby the extension rods 68′, 68″ is articulatedonto an articulation location 70′, 70″ of the related front support boom42′, 42″, situated at a distance from the bearing location 48′, 48″,with their other end. The articulation locations 64′, 66′ and 64″, 66″,respectively, are disposed on the deflection lever 62′ or 62″,respectively, at a distance from one another, in each instance. Thekinematics of the activation mechanisms for the front support booms 42′,42″ can best be explained using FIG. 3 a to c, 4 a and b, as well as 5 aand b. In the transport position according to FIG. 3 a to c, the frontsupport booms 42′, 42″ point to the rear, parallel to the longitudinalchassis axis, and lie against the side flanks of the semi-trailer 14there. In this position, the cylinder/piston units 54′, 54″ are in theirextended end position, so that they enclose their smallest angle withthe related deflection lever 62′, 62″, while the extension rods 68′, 68″enclose their greatest angle with the deflection lever 62′, 62″.

During the course of the extension procedure, the cylinder/piston unit54′ is shortened by retraction of the piston rod. At the same time, therelated deflection lever 62′ is pivoted forward, into the clear space 72between the semi-trailer 14 and the tractor unit 12, so that the frontsupport boom 42′ is pivoted outward, by way of the extension rod 68′. Inthe pivot position shown in FIGS. 4 a and b, the support boom 42′ hasreached a first support position, which corresponds to the so-callednormal support. In this position, the support boom 42′ comes up againsta stop 76, which is fixed in place on the chassis, with a contact arm74. As can be seen in FIGS. 4 a and b, the cylinder/piston unit 54′ hasnot yet been completely moved in in this position. Accordingly, anadditional support position according to FIGS. 5 a and b can beapproached, from the position according to FIGS. 4 a and b, by means offurther shortening of the cylinder/piston unit 54′, in which the frontsupport leg 42′ is pivoted in close to the tractor unit 12. This is theso-called narrow support, which can be selected for tight set-uplocations. In order to reach this support position, first the stop 76has to be released by hand, so that the contact arm 74 can move past it(see FIG. 5 b). In the narrow support, the cylinder/piston unit 54′ getsinto its moved-in end position, while the deflection lever 62′, togetherwith the extension rod 68′, are pivoted even further into the clearspace 72, and utilize this space almost completely, in terms of itswidth. Corresponding kinematics result for the support boom 42″ and itsactivation mechanism, as well.

Because of the kinematics of the activation mechanism, a constant feedof pressurized oil to the cylinder/piston unit 54′, 54″ would lead to anon-uniform angular velocity during pivoting out of the front supportlegs 42′, 42″. In order to avoid this, the feed of pressurized oil tothe cylinder/piston unit 54′, 54″ is varied as a function of the angularposition of the related front support boom 42′, 42″ or of the deflectionlever 62′, 62″. This is done, for example, in that a throttle valve 104is disposed in a pressure agent feed line 102 to the cylinder/pistonunit 54′, 54″, which valve can be controlled by way of a switching organ106 that responds in a defined angular position of the support boom 42′,42″.

In order to guarantee secure support, the front and rear support boomsof the support construction 38 are brought into their support position,one after the other, and secured there. This is done using a remotecontrol activated by the operator.

It is practical if the superstructures described above, which relate tothe concrete pump and the support construction, are situated on asuperstructure frame that is set onto the chassis of the semi-trailer inthe partly pre-assembled state, and connected with it.

A unique feature of the mobile work machine that has a tractor-traileras a chassis 10 consists in that the tractor unit 12 and thesemi-trailer 14 can be pivoted, relative to one another, in multipledegrees of freedom, by way of the fifth-wheel coupling 16. Since, on theother hand, the weight of the tractor unit 12 is needed as a ballastweight to stabilize the semi-trailer 14 that is supported on the surface40 with the support booms 42′, 42″, 44, in the raised position,particularly in the case of concrete pumps having large distributormasts 30, additional measures are required. These consist, inparticular, in that the semi-trailer 14 has special means for raisingand holding the tractor unit 12 in place. In order to keep the spacerequired for these means as small as possible, a unique feature of theinvention consists in that the bearing locations 48′, 48″ of the frontsupport booms 42′, 42″ have an axis-central, continuous cavity 80, andthat the means disposed on the semi-trailer 14 for raising and holdingthe tractor unit 12 in place, each have a lifting element 82 that passesthrough the central cavity 80 of the bearing location 48′, 48″, from topto bottom, and can be fixed in place on the tractor unit 12. In thisconnection, it is practical if the cavity 80 is situated in a bearingpin 81 that is fixed in place on the support boom. The lifting elements82 are disposed so that they can be raised and lowered relative to thesemi-trailer 14, by means of a hydromotor 84, in each instance, andcarry a coupling organ 86 at their lower end. The lifting elements 82 inturn are coupled with the related hydromotor 84 by way of a linear drive88, in each instance, the thread parts of which are configured as atrapezoid thread. As can particularly be seen in FIGS. 7 a and b, thecoupling organ 86 is configured as an oval ring articulated onto thelower end of the lifting element 82, which ring can be rotated, relativeto the lifting element 82, about its longitudinal axis, and can bepivoted about a transverse axis 83.

In order to be able to connect the lifting elements 82, with theircoupling organs 86, with the tractor unit 12 in the support position,the tractor unit 12 has an auxiliary frame 90 that has two arc-shapedsegments 94, concentric to the vertical axis 92 of the king pin 18,which segments in turn are provided with oblong holes 96 that arecorrespondingly curved in arc shape and open toward the top, and withlocking locations that are disposed at a grid distance from one anotherand configured as holes 98. Coupling of the lifting elements 82 with thetractor unit 12 takes place in that the coupling organs 86, configuredas oval rings, are introduced into the related segment 94 of theauxiliary frame. 90 through one of the oblong holes 96, in eachinstance, and are fixed in place on the auxiliary frame 90 at one of thelocking locations 98, with a socket pin 100. Using these measures, it ispossible to couple the tractor unit 12 with the semi-trailer 14 atdifferent angles of rotation about the vertical axis 92. This has provento be particularly advantageous, because when a tractor-trailer is setup in a support position, the tractor unit 12 will not always beoriented parallel to the semi-trailer 14. In the coupled position, thelifting elements 82 and the fifth-wheel coupling 16 form a connectiontriangle that ensures that all the wheels of the tractor unit 12 areraised from the surface 40 when the semi-trailer 14 is supported by wayof the support construction.

In the travel state, the lifting elements 82 are raised so far, afterthe socket pins 100 are removed, by way of the hydromotors 84, that thecoupling organs 86 are retracted into the cavity 80 (FIG. 7 b). In thisstate, the tractor unit 12 and the semi-trailer 14 can be moved,relative to one another, in the degrees of freedom of the fifth-wheelcoupling 16.

In summary, the following should be stated: The invention relates to amobile work machine, particularly a mobile concrete pump, having achassis 10 designed as a tractor-trailer. The tractor-trailer has atractor unit 12 and a multi-axle semi-trailer 14 that carries the workmachine and is connected with the former by means of a fifth-wheelcoupling 16. In the region of the semi-trailer 14, there is a supportconstruction 38 that can be supported on a surface 40, raising thetractor-trailer. The support construction 38 comprises two front supportbooms 42′, 42″ and two rear support booms 44, which can be pivotedbetween a transport position and at least one support position, relativeto the semi-trailer, in each instance. Furthermore, means for raisingthe tractor unit 12 and holding it in place are provided on thesemi-trailer 14, so that the tractor unit 12 forms a ballast weight forstabilizing the semi-trailer 14, which is supported on the surface 40with the support construction 38, in the support position. The inventionprovides that the activation mechanism of each front support boom 42′,42″ has a cylinder/piston unit 54′, 54″ configured as a hydrocylinder,which extends beyond the face part 52 of the semi-trailer 14, which unitis articulated, at its one end, directly with a bearing eye 56′, 56″that is fixed in place on the semi-trailer, and, at its other end,indirectly with the related support boom 42′, 42″, by way of adeflection gear mechanism 58′, 58″.

1. Mobile work machine having a chassis (10) that is designed as atractor-trailer, a multi-axle tractor unit (12) and a multi-axlesemi-trailer (14) that carries the work machine and is connected withthe tractor unit by means of a fifth-wheel coupling (16), having asupport construction (38) that is disposed in the region of thesemi-trailer (14) and can be supported on a surface, raising thetractor-trailer, which construction has two front support booms (42′,42″) disposed at bearing locations (48′, 48″) on the tractor unit end ofthe semi-trailer (14), symmetrical to the longitudinal chassis axis,which can be pivoted between a transport position and at least onesupport position, by means of a hydraulically driven activationmechanism, in each instance, and two rear support booms (44) that can bepivoted between a transport position and at least one support position,whereby the semi-trailer (14) has means for raising and holding thetractor unit (12) in place, wherein the activation mechanism of eachfront support boom (42′, 42″) has a cylinder/piston unit (54′, 54″)configured as a hydrocylinder, which extends beyond the face part (52)of the semi-trailer (14), which unit is articulated, at its one end,directly with a bearing eye (56′, 56″) that is fixed in place on thesemi-trailer, and, at its other end, indirectly with the related supportboom (42′, 42″), by way of a deflection gear mechanism (58′, 58″). 2.Mobile work machine according to claim 1, wherein the cylinder/pistonunits (54′, 54″) assigned to the two front support booms (42′, 42″) aredisposed one above the other, on the face (52) of the semi-trailer (14),facing toward opposite sides.
 3. Mobile work machine according to claim1, wherein the bearing eyes (56′, 56″) of the cylinder/piston units(54′, 54″) assigned to the two front support booms (42′, 42″), whicheyes are fixed in place on the semi-trailer, are disposed on the side ofthe semi-trailer (14) that faces the other front support boom (42″,42′), in each instance.
 4. Mobile work machine according to claim 3,wherein the bearing eyes (56′, 56″) of the cylinder/piston units (54′,54″) assigned to the two front support booms (42′, 42″), which eyes arefixed in place on the semi-trailer, are disposed in the vicinity of thebearing location (48″, 48′) of the other front support boom (42″, 42′),in each instance.
 5. Mobile work machine according to claim 1, whereinthe deflection gear mechanism (58′, 58″) assigned to the activationmechanism of each front support boom (42′, 42″) has a deflection lever(62′, 62″) that can be pivoted about an articulation axis parallel tothe extension axis of the related support boom (42′, 42″), on anarticulation (60′, 60″) that is fixed in place on the semi-trailer, withits one end, which lever has articulation locations (64′, 64″; 66′, 66″)at its other end, on which the cylinder/piston unit (54′, 54″) as wellas the one end of a rigid extension rod (68′, 68″) are articulated,whereby the extension rod (68′, 68″) is articulated, with its other end,on an articulation location (70′, 70″) of the support boom (42′, 42″)disposed at a distance from the bearing location (48′, 48″).
 6. Mobilework machine according to claim 5, wherein the articulation locations(64′, 66′; 64″, 66″) for the cylinder/piston unit (54′, 54″) and for theextension rod (68′, 68″), which are situated at the other end of thedeflection lever (62′, 62″), are disposed at a distance from oneanother.
 7. Mobile work machine according to claim 1, wherein all thebearing and articulation axes of the activation mechanism are orientedparallel to the extension axis of the related support boom (42′, 42″).8. Mobile work machine according to claim 1, wherein the feed ofpressure agent to the cylinder/piston unit (54′, 54″) can be changed asa function of the angular position of the related front support boom(42′, 42″) or deflection lever (62′, 62″).
 9. Mobile work machineaccording to claim 8, wherein a throttle valve (104) is disposed in apressure agent feed line (102) to the cylinder/piston unit (54′, 54″),which valve can be controlled by way of a switching organ (106) that canbe switched in a defined angular position of the support boom (42′, 42″)or of the deflection lever (62′, 62″).
 10. Mobile work machine accordingto claim 1, wherein the front support booms (42′, 42″) lie against areleasable stop (76) in a first support position, and against an endstop in a second support position.
 11. Mobile work machine according toclaim 1, wherein the bearing locations (48′, 48″) of the front supportbooms (42′, 42″) have a continuous, axis-central cavity (80), andwherein the means disposed on the semi-trailer (14) for raising andholding the tractor unit in place each have a lifting element (82) thatpasses through the central cavity (80) of the bearing locations (48′,48″), from top to bottom, and can be releasably fixed in place on thetractor unit (12).
 12. Mobile work machine according to claim 11,wherein the cavity (80) is disposed in a bearing pin (81) that is fixedin place on the support boom.
 13. Mobile work machine according to claim11, wherein the lifting elements (82), which can be raised and loweredby means of a motor (84), in each instance, carry a coupling organ (88)at their lower end, and wherein the tractor unit (12) carries anauxiliary frame (90) on which the coupling organs (86) of the liftingelements (82) can be locked in place.
 14. Mobile work machine accordingto claim 13, wherein the lifting elements (82) are coupled with therelated motor (84) by way of a linear drive (88), in each instance. 15.Mobile work machine according to claim 14, wherein the linear drive (88)is configured as a trapezoid thread at its thread parts.
 16. Mobile workmachine according to claim 13, wherein the fifth-wheel coupling (16) hasa king pin (18) disposed in the center, and wherein the auxiliary frame(90) is configured in the shape of an arc, in its outline, and disposedconcentric to the axis (92) of the king pin (18), and has multiplelocking locations (98) for the coupling organs (86) of the liftingelements (82), disposed at a distance from one another in thecircumference direction.
 17. Mobile work machine according to claim 16,wherein the coupling organs (86) can be fixed in place at the lockinglocations (98) by means of socket pins (100).
 18. Mobile work machineaccording to claim 16, wherein the coupling organs (86) are configuredas oval rings that can be rotated and pivoted on the lifting element(82) and engage into oblong arc-shaped holes (96) of the auxiliary frame(90), and wherein the locking locations (98) form a hole grid in theauxiliary frame (90), which runs in the circumference direction, on theholes of which the coupling organs (86) can be fixed in place by meansof socket pins (100).
 19. Mobile work machine according to claim 11,wherein in the transport position, the coupling organs (86) can beretracted into the cavity (80) of the related bearing locations (48′,48″), by means of a motor, by way of the lifting element (82). 20.Mobile work machine according to claim 1, wherein the support booms(42′, 42″; 44) that form the support construction (38), and the workmachine, are disposed on at least one superstructure frame rigidlyconnected with the semi-trailer (14).
 21. Mobile work machine accordingto claim 1, wherein the work machine is configured as a concrete pumpthat has a pump unit (36) disposed on the semi-trailer (14) or on thesuperstructure frame, having a material application container (34) and afeed line (32) that is connected with the pressure output of the pumpunit (36), guided by way of a distributor mast (30).